64bit kernel has already had its atomic64 functions. Except for that, we
use the generic spinlocked version. The atomic64 types and related
functions are needed for the Linux performance counter subsystem.
Signed-off-by: Deng-Cheng Zhu<dengcheng.zhu@gmail.com>

I already acked this once, so you can (should) add my...
Acked-by: David Daney <ddaney@caviumnetworks.com>

Really, this part is correct and standalone, so I think Ralf should just
go ahead and merge it to his queue.